No Placebo Effect from Carbohydrate Intake during Prolonged Exercise


The research study, “No Placebo Effect from Carbohydrate Intake during Prolonged Exercise,” was conducted to find out if a placebo substance- artificially colored and flavored water (PLA) had any effect on athletes’ performance- whether it improved performance in a prolonged exercise. The researchers hypothesized that “a placebo effect would be present, but nonetheless significantly less than the real effect of CHO intake” (Hulston and Jeukendrup, 276). Ten endurance trained cyclists were selected and subjected to the same experiment conditions- (time and environment) and a beseline WAT trial. During the experiment sessions which lasted 120 minutes each, with the last 60 minutes targeted as the trial time (TT), they were given three different drinks- plain water (WAT), colored and flavored water (PLA) and a carbohydrate-electrolyte solution (CES). The performance of participants who had ingested the PLA solution was compared against those who had taken either WAT or CES. It was found out that participants’ performance improved when they ingested CES, while there was no significant difference between WAT and PLA on performance. At the end of the experiment, it was demonstrated that “simply believing that one has received CHO does not improve performance during prolonged exercise” (Hulston and Jeukendrup 282), hence the conclusion that there is no placebo effect from carbohydrate intake during prolonged exercise.


Discussion and Critical Analysis

The reliability of the research findings is tied to the methodology employed by the researchers. By adopting a double blind approach, participants under PLA were not aware of its neutral effect, hence believed that they could perform as well as those under CES. This was significant in demonstrating the real effect of CHO intake as opposed to a placebo substance. Similarly, the random order in which participants for the PLA experiment were chosen ensured that the results were not compromised by participants’ knowledge of what they had ingested. Similarly, plain water served as a control by measuring the baseline performance of the participants, thereby helping the researchers to detect when the athletes’ performance improved as a result of either a placebo effect or the real effect of CHO.

The results of the study and its conclusions demonstrate that the mechanism of a real substance’s action (in this case the carbohydrate electrolyte solution) is different from a placebo. A placebo substance, properly speaking, is an agent administered with the purpose of deceiving the recipient of its effects, so as to condition him/her to respond or react in a certain manner. In this particular experiment, the PLA solution was the placebo used to make the participants believe that their performance will improve due to the beneficial effect of CHO (what they thought they had ingested) during prolonged exercise. By making them have similar expectations as those who had taken CHO, they worked out their best, to the limits of their efforts, beyond which point the real effect of CHO emerged by enhancing performance. The difference in performance between PLA and CES groups, and the latter’s relatively neutral effect in comparison to WAT proved that PLA did not have a placebo effect, even when the participants believed it was a real performance enhancer. This is due to the fact that while CHO contained significant amounts of glucose and fructose which supplemented the body’s glycogen reserves, the PLA solution was essentially as bare of nutrients as plain water.

This notwithstanding, however, the summative conclusions drawn from the experiment ignored the slight different between PLA and water (a 4.5 improvement compared to plain water), which suggests a considerable placebo effect achieved by the PLA solution. As noted before, a placebo effect is largely psychological, in that its real significance lies in what the participants think, rather than what they manage to accomplish on the basis of their belief. In the current experiment, it is evident that those who had ingested PLA believed they could improve in their performance as a result of the real beneficial effect of CHO supplements. Consequently, they were motivated and in effect performed a little better than those who had ingested plain water, because they lacked this motivation. However, the absence of carbohydrates in the PLA solution became apparent when their performance dropped before those under CHO, because motivation alone could not overcome the fatigue resulting from physical exhaustion, in which case carbohydrate supplements came in handy for those who had taken the real CHO supplement- CES.

In this regard, it could be argued that the marginal difference exhibited by participants when they ingested PLA in comparison to WAT manifests a placebo effect, the extent of the effect notwithstanding. Accordingly, one of the study’s major shortcomings is its conclusion, which ignores a very critical aspect of the study. By measuring the participants performance, the aim of the study was to investigate a psychological aspect, namely how the belief that participants had ingested a carbohydrate supplement influenced their performance.  By emphasizing on the physiological effect of CHO and its absence in PLA shifted the research’s focus a little bit, explaining the difference in the hypothesis and the conclusion. In fact, the findings of the research are more reflective of the hypothesis than they are of the conclusion, in the sense that PLA and WAT did not have similar effects per se. The difference, as argued before, is a result of a placebo effect brought about by the PLA solution.

In conclusion, the study was very spot-on with its hypothesis and generally accurate with its conclusion as demonstrated by the results of the experiment. The real effect of a placebo agent is mainly psychological, whose purpose is to induce a psychological response from its recipient. As pertains to athletics, performance enhancers have both a psychological and physiological effect, in that the athlete is first motivated by the knowledge of their benefit, and secondly through their metabolism which supplements the body’s energy reserves during prolonged exercise.

A critical issue that comes to mind at this point is the real effect of enhancement drugs such as aneroid steroids. While it is clear that they have no nutritional value and therefore do not add to the body’s reserves, it can be argued that their main function is to speed up the oxidation process of body fats and carbohydrates. This is the reason why they are common for short-duration athletes- since the body’s reserves get exhausted in prolonged exercise, hence nothing to oxidize or ‘speed up,’ for that matter. In this light, it is advisable for athletes, especially those involved in prolonged exercises, to choose supplements whose nutritional value is real and verifiable. In the end, as demonstrated by the research study, what matters is their nutritional contribution to body metabolism, and not the psychological conditioning of the mind. While a placebo effect-induced motivation is important, it cannot sustain the body’s physiological need when it is physically exhausted, hence the need for a real nutritional supplement.




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